1. Field of the Invention
The invention relates to a spring hinge for eyewear, that enables to open the temples of eyeglasses beyond the regular position of use and that is intended for use with the temples of eyeglasses with the characteristics set forth in the introductory clause of claim 1.
2. Description of the Related Art
From patent EP 90 107 388 are known spring hinges for eyewear that allow the opening of the temples beyond the regular position of use and that are intended for use with the temples of eyeglasses. Such a hinge spring is provided with a locking element having a U-shaped cross section, presenting a projection on the first of its legs on its free end toward the outside, in which the locking element is lodged in a sliding element and in a first recess of same in such a manner, that its two legs point away from the axis of the hinge. The locking element abuts in a spring-loaded manner the shoulder of a second recess with its projection, thus constituting a stop for a spring plunger.
Furthermore, from GB-2 248 121 A is known a spring hinge for eyewear, in which a cylindrical locking element is provided with a circular shoulder, wherein the locking element is diametrically divided by a slot. The shoulder engages in a recess provided in the temple of the glasses.
A disadvantage of such a design of the spring hinge is that the locking effect by the locking element can be obtained only by a spring tension acting upon the locking element, since the locking element is spread by the spring itself or by a spring plunger. A further disadvantage is that a spring guide pin must preload the required spring to ensure that the locking effect is attained. This, in turn, has the disadvantage that the assembly is relatively costly and difficult.
The present invention has the task to further develop the known hinge, so that an interlocking of the locking element with the frame is automatically attained.
In accordance with the invention, this task is solved by the object of claim 1. Further advantageous embodiments are objects of the subclaims.
The spring hinge according to the invention is characterized by the fact that the locking element presents at least one snap-in pin bent in direction of the wall of the recess. Because of the bent, spring snap-in pin occurs an automatic locking of the snap-in pin in the stepped recess. Therefore, no additional preloading is required, which reduces the assembly costs.
In the case of a locking element designed in one piece, the snap-in pin or the snap-in pins can be produced at the same time as the locking element is prepared and/or manufactured. Therefore, the manufacture of the snap-in pin together with the locking element does not require any additional components that must be connected to the locking element.
In the case of a locking element that presents a top from which extend the snap-in pins, and in which a sliding element is installed in a slidable manner between the snap-in pins, on one hand, such locking element ensures the locking and, on the other hand, the locking element itself guides the sliding element.
Therefore, the locking element has two operational functions. This design of the locking element minimizes the number of elements making up the spring hinge.
If the locking element is designed in such a manner that it presents a recess into which the snap-in pin can be lowered, the dimensions of the locking element or of the recess in the temple of the glasses, respectively, are reduced, since the snap-in pin is lowered into the recess at the time of its assembly, and it snaps into the second recess after having reached it from the recess in the locking element.
The snap-in pin or snap-in pins, respectively, can be produced from a lamina, that is a stamped metal part. This design has the advantage that the locking element can be manufactured in a simple manner, which makes it cost-effective. The snap-in pins are then bent away from the lamina. The bending angle is less than 90xc2x0.
In order to prevent the danger of breaking, it is advantageous if the locking element is made out of a T-shaped blank, whereby the top of the T-shaped blank is bent partly cylindrically. This has the advantage that, e.g., in the case of spring hinges with a recess in which is installed a spring guide pin, the spring guide pin extends along the cylindrical part of the locking element, which would obviate the need of manufacturing an opening for the spring guide pin.
The two legs of the T-shaped blank are advantageously designed at a angle to each other. After the blank is bent, a locking element with a slot for a guide pin. The slot is of such dimensions, that the locking element rests with play on the guide pin. The bent locking element presents a tilted plane opposite the longitudinal axis of the spring hinge, so that, because of the effect of a spring resistance, the snap-in pin engages into the recess.
Prior art spring hinged eye glasses or spectacles have the disadvantage that the spring is fully compressed when the bows are spread apart substantially beyond their normal position. This extended out-turning of the bows can result in damage of the spring or other parts of the spring hinge.
The prior art structures use stops which limit the outward movement of the bow beyond a normal position. Such structure is shown in U.S. Pat. No. 4,991,258 and in German Utility Model G11417. For example, in the German Utility Model there is disclosed an external stop for preventing excessive outward movement of the bow. The difficulty with this construction utilizing an external stop is that a manufacturer is not able to guarantee the proper function, since the function mostly depends on the work of the frame manufacturer who links the middle part or frame and the bow by the spring hinge.
In U.S. Pat. No. 4,991,258 the spring hinge disclosed uses an internal stop. However, this solution is complicated and requires a number of additional parts. It lacks simplicity.
It is an object of the improvement here to provide a spring hinge having a stop which is easily fabricated and which enables the manufacturer to guarantee the function of the stop.